Liquid crystal apparatus with gradation information signals and DC bias
Patent 5396352 Issued on March 7, 1995. Estimated Expiration Date: 
March 7, 2012. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
March 7, 2012. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesDriving method for liquid crystal device Ferroelectric liquid crystal matrix driving apparatus and method Method of driving a ferroelectric liquid crystal display device and associated display device to achieve gray scale Ferroelectric liquid crystal display having opposingly inclined alignment films wherein the liquid crystal has one twisted and two aligned states which coexist and a driving method to produce gray scale Apparatus and method for driving an optical printer having a liquid crystal optical switch Liquid crystal device having insulating and alignment films wherein three ࣙ-CR[-2.3+ln(C/Ps)] Liquid crystal apparatus and driving method therefor Method of driving ferroelectric liquid crystal element Patent #: 5227900 InventorsAssigneeApplicationNo. 746338 filed on 08/16/1991US Classes:349/37, Polarity based driving345/97, Ferroelectric liquid crystal elements349/34, With application of holding or bias voltage (i.e., voltage which does not change the optical state of the liquid crystal)349/138, Insulating layer349/173Greyscale resulting from liquid crystal property other than solely Smectic AExaminersPrimary: Gross, Anita PellmanAssistant: Duong, Tai V. Attorney, Agent or FirmForeign Patent References
International ClassesG09G 003/130G02F 001/133 ClaimsWhat is claimed is: 1. A liquid crystal apparatus comprising a liquid crystal panel having a pair of electrodes and a liquid crystal exhibiting spontaneous polarization and arranged between said pair of electrodes, first means for applying a gradation voltage signal corresponding to gradation information to said pair of electrodes, and second means for applying, a DC component serving as a reverse bias of an internal electric field generated upon application of the gradation voltage signal, to said liquid crystal during one vertical scanning period. 2. An apparatus according to claim 1, wherein said liquid crystal essentially consists of a ferroelectric liquid crystal. 3. An apparatus according to claim 1, wherein said one vertical scanning period is one frame scanning period. 4. An apparatus according to claim 1, wherein a value of the DC component is within a range of 1/50 to 1/5 of the gradation voltage signal. 5. A liquid crystal apparatus comprising: a. a liquid crystal panel having switching elements arranged along a plurality of rows and a plurality of columns, first wiring lines commonly connecting first terminals of said switching elements in units of rows, second wiring lines commonly connecting second terminals of said switching elements in units of columns, a plurality of pixel electrodes connected in units of third terminals of said switching elements, counter electrodes opposite to said pixel electrodes, and a liquid crystal exhibiting spontaneous polarization and sandwiched between said plurality of pixel electrodes and said counter electrodes; b. first means for applying scanning pulses to said first wiring lines; and c. second means for applying a gradation voltage signal corresponding to gradation information to said second wiring lines and for applying an auxiliary voltage signal to said second wiring lines so that a DC component serving as a reverse bias for an internal electric field generated upon application of the gradation voltage signal is applied to said liquid crystal during one vertical scanning period. 6. An apparatus according to claim 5, wherein said liquid crystal essentially consists of a ferroelectric liquid crystal. 7. An apparatus according to claim 5, wherein said one vertical scanning period is one frame scanning period. 8. An apparatus according to claim 5, wherein a value of the DC component is within a range of 1/50 to 1/5 of the gradation voltage signal. 9. A liquid crystal apparatus comprising: a. a liquid crystal panel having switching elements arranged along a plurality of rows and a plurality of columns, first wiring lines commonly connecting first terminals of said switching elements in units of rows, second wiring lines commonly connecting second terminals of said switching elements in units of columns, a plurality of pixel electrodes connected in units of third terminals of said switching elements, counter electrodes opposite to said pixel electrodes, and a liquid crystal exhibiting spontaneous polarization and sandwiched between said plurality of pixel electrodes and said counter electrodes; b. first means for applying scanning pulses to said first wiring lines; and c. second means for applying a voltage signal corresponding to gradation information to said second wiring lines after a reset voltage signal is applied and for applying an auxiliary voltage signal to said second wiring lines such that a DC component serving as a reverse bias for an internal electric field generated upon application of the gradation voltage signal is applied to said liquid crystal during one vertical scanning period. 10. An apparatus according to claim 9, wherein said liquid crystal essentially consists of a ferroelectric liquid crystal. 11. An apparatus according to claim 9, wherein said one vertical scanning period is one frame scanning period. 12. An apparatus according to claim 9, wherein a value of the DC component is within a range of 1/50 to 1/5 of the gradation voltage signal. 13. An apparatus according to claim 9, further comprising means for applying, prior to application of the reset voltage signal, a voltage signal given such that a difference between an absolute value of the reset voltage signal and an absolute value of the gradation voltage signal becomes zero. 14. An apparatus according to claim 9, further comprising means for applying a zero voltage during a period between the auxiliary voltage signal and the gradation voltage signal. 15. A liquid crystal apparatus comprising: a liquid crystal element having a liquid crystal having spontaneous polarization, a pair of electrode substrates for sandwiching said liquid crystal therebetween, and insulating layers formed between said electrode substrates and said liquid crystal, wherein a spontaneous polarization ##EQU24## value of said liquid crystal, an interelectrode composite capacitance ##EQU25## of Vth (units of V) of optical response of said liquid crystal in said liquid crystal element satisfy the following condition: ##EQU26## first means for applying a gradation voltage signal corresponding to gradation information to said pair of electrodes; and second means for applying a DC component, serving as a reverse bias of an internal electric field generated upon application of the gradations voltage signal, to said liquid crystal during one vertical scanning period. 16. An apparatus according to claim 15, wherein said liquid crystal essentially consists of a ferroelectric liquid crystal. 17. An apparatus according to claim 15, wherein said one vertical scanning period is one frame scanning period. 18. An apparatus according to claim 15, wherein a value of the DC component is within a range of 1/50 to 1/5 of the gradation voltage signal. 19. A liquid crystal apparatus comprising: a. a liquid crystal element having switching elements arranged along a plurality of rows and a plurality of columns, first wiring lines commonly connecting first terminals of said switching elements in units of rows, second wiring lines commonly connecting second terminals of said switching elements in units of columns, a plurality of pixel electrodes connected in units of third terminals of said switching elements, counter electrodes opposite to said pixel electrodes, a liquid crystal exhibiting spontaneous polarization PS (nC/cm2) sandwiched between said plurality of pixel electrodes and said counter electrodes, and an insulating member formed on at least one of said pixel and counter electrodes, a voltage threshold value Vth (V) of optical response of said liquid crystal and an interelectrode capacitance Ci (nF/cm2) of said insulating member satisfying the following condition: ##EQU27## b. first means for applying scanning pulses to said first wiring lines; and c. second means for applying a gradation voltage signal corresponding to gradation information to said second wiring lines and for applying an auxiliary voltage signal to said second wiring lines so that a DC component serving as a reverse bias for an internal electric field generated upon application of the gradation voltage signal is applied to said liquid crystal during one vertical scanning period. 20. An apparatus according to claim 19, wherein said liquid crystal essentially consists of a ferroelectric liquid crystal. 21. An apparatus according to claim 19, wherein said one vertical scanning period is one frame scanning period. 22. An apparatus according to claim 19, wherein a value of the DC component is within a range of 1/50 to 1/5 of the gradation voltage signal. 23. A liquid crystal apparatus comprising: a. a liquid crystal element having switching elements arranged along a plurality of rows and a plurality of columns, first wiring lines commonly connecting first terminals of said switching elements in units of rows, second wiring lines commonly connecting second terminals of said switching elements in units of columns, a plurality of pixel electrodes connected in units of third terminals of said switching elements, counter electrodes opposite to said pixel electrodes, a liquid crystal exhibiting spontaneous polarization PS (nC/cm2) and sandwiched between said plurality of pixel electrodes and said counter electrodes, and an insulating member formed on at least one of said pixel and counter electrodes, a voltage threshold value Vth (V) of liquid crystal of said optical response and an interelectrode capacitance Ci (nF/cm2) said insulating member satisfying the following condition: ##EQU28## b. first means for applying scanning pulses to said first wiring lines; and c. second means for applying a voltage signal corresponding to gradation information to said second wiring lines after a reset voltage signal is applied and for applying an auxiliary voltage signal to said second wiring lines such that a DC component serving as a reverse bias for an internal electric field generated upon application of the gradation voltage signal is applied to said liquid crystal during one vertical scanning period. 24. An apparatus according to claim 23, wherein said liquid crystal essentially consists of a ferroelectric liquid crystal. 25. An apparatus according to claim 23, wherein said one vertical scanning period is one frame scanning period. 26. An apparatus according to claim 23, wherein a value of the DC component is within a range of 1/50 to 1/5 of the gradation voltage signal. 27. An apparatus according to claim 23, further comprising means for applying, prior to application of the reset voltage signal, a voltage signal given such that a difference between an absolute value of the reset voltage signal and an absolute value of the gradation voltage signal becomes zero. 28. An apparatus according to claim 23, further comprising means for applying a zero voltage during a period between the auxiliary voltage signal and the gradation voltage signal. Other References
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